1. Field of the Invention
The present invention relates to a load sensing system for sensing a load, which is applied to a seat.
2. Description of Related Art
A load sensing system is used to, for example, determine a state of an occupant who is seating on a vehicle seat. Such a load sensing system includes front and rear sensors (see, for example, Japanese Unexamined Patent Publication No. 2003-14528, which corresponds to U.S. Pat. No. 6,759,604). For instance, the front sensors of the load sensing system may include a pair of front sensors, which are arranged in two front corners of the seat. Also, the rear sensors of the load sensing system may include a pair of rear sensors, which are arranged in two rear corners of the seat. Each front sensor senses a load, which is applied to a front part of the seat. Each rear sensor senses a load, which is applied to a rear part of the seat. An occupant sensing electronic control unit (ECU) determines a state of the occupant on the seat based on a result of a sum value computing operation for computing a sum value of the sensed load signals of the front and rear sensors.
Here, an entire load sensing range of each sensor needs to be set to a corresponding range, which is determined based on, for example, a weight of the seat, a flexing of a seat frame at the time of installing the seat frame to the seat and a vehicle body, an weight of the occupant, a vibration generated at the time of driving the vehicle, a dynamic change caused by a steering operation of the vehicle. However, when a size of the entire load sensing range of each sensor is increased, the load sensing accuracy of the sensor is disadvantageously reduced. In other words, an occupant determining performance of the occupant sensing ECU for determining the state of the occupant is disadvantageously deteriorated.